Background

In general, primary tumors of the heart are rare. In autopsy studies, the overall prevalence ranges from 0.002% to 0.33%, with about 75-79% of these considered benign.
[1, 2]

Although most tumors of the heart are benign, because of their malignant potential, the risks secondary to impaired cardiac function (eg, congestive heart failure, inflow/outflow tract obstruction), conduction system involvement, and/or peripheral embolism mandate prompt evaluation and definitive treatment.

It has been reported that patients with benign cardiac tumors are at increased risk of first ischemic stroke, particularly patients younger than 50 years.
[3]

The most common primary cardiac tumor is a myxoma. Other less common neoplastic tissue types occur; each has distinguishing characteristics that often aid in accurate preoperative diagnosis or diagnosis prior to death. A definitive diagnosis is important because some cardiac tumors can be malignant or, more commonly, can represent metastasis from a distant primary tumor.

Pathophysiology

Myxomas arise usually from the endocardium and range in size from 1-20 cm. The vast majority (86%) develop from the left atrium, with the remainder developing from the right atrium.
[4] They tend to develop from the fossa ovalis but can be found arising from anywhere in the atrium. Ventricular or valvular sites are rare.

Rhabdomyomas are intramural tumors that are typically smaller and most often involve the left (80%) or right (15%) ventricles.

Fibromas most commonly involve the intraventricular septum or left ventricular free wall. Less than 10% of reported cases have atrial or great vessel involvement. Unlike myxomas, tumor embolization is uncommon. Tumor growth can displace or directly involve mitral and aortic valves and result in hemodynamically significant valvular stenosis or regurgitation.

Symptoms are typically secondary to adverse effects on normal left ventricular geometry, filling, and ejection. Additionally, arrhythmias, particularly sudden death and abnormal atrioventricular conduction, are common because of tumor disruption of the nodal or septal conduction tissue. Benign cardiac tumors can also present without symptoms as incidental findings found on cardiac studies investigating other pathology.

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Etiology

The precise etiology of benign cardiac tumors is unknown.

There may be a causal association with Gorlin syndrome, as follows:

Syndrome of multiple nevoid basal-cell carcinomas, cysts and fibrosarcomas of the jaws, and skeletal abnormalities

Sex- and age-related demographics

No known sex predilection is recognized, although the rarity of the different benign cardiac tumors prevents accurate determination of a male-to-female ratio.

Myxomas are the most common tumors in adults. However, rhabdomyoma is the most common tumor in children (second most common benign cardiac tumor overall). Fibromas are rare and typically occur in children.

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Prognosis

Morbidity/mortality

The prognosis is excellent, including disease-free survival, if the tumor is completely resected.
[5] Incomplete resections predispose patients to further tumor growth and recurrence of symptoms; risk is undefined.

Although unproved, concern for recurrence, similar to that for fibromas found in other parts of the body, is warranted.

Systemic embolization is the most common causes of complications. It is typically a presenting symptom in 25-50% of cases. Embolization can occur to any end organ including the brain, lower extremities, kidneys, and heart (coronary artery) with subsequent ischemia and possible infarction. Cardiac tumor should be in the differential diagnosis when evaluating any cause of embolization. Rhabdomyomas often manifest early in life with inflow/outflow obstruction (ie, heart failure) or arrhythmia and resection is typically indicated.

Despite complete resection, patients are still at risk for sudden death due to damage to the conduction system.

The role of prophylactic antiarrhythmics or implanted cardioverter/defibrillators is undefined.

The authors and editors of Medscape Drugs & Diseases gratefully acknowledge the contributions of previous authors Michael S Firstenberg, MD, and James D Thomas, MD, to the development and writing of this article.